Don't Lick the Windows: And Other Lessons I Learned While Teaching

That's the full title of my blog but unfortunately it wouldn't all fit as the official title. 
This will be a collection of random interesting, funny, horrifying, bizarre and often weird things I have experienced in my profession as a teacher. 
I can't tell you my real name, or where I live.  But I promise that everything I say on here is the absolute truth, with no poetic license taken to make it sound more interesting. Everything I write here actually happened.

Lesson Number One: Don't Lick the Windows
Maybe that is an obvious thing that most people don't actually have to learn.  I would also like to add that I never actually licked any windows before this event, but I still think it is pertinent to know.
Why shouldn't you lick the windows at my school? Because there is a high possibility that you are licking somebody else's phlegm.
My friend the art teacher told me a few days ago that some boys were slagging on the art-room window.  Apparently it is great fun...
Then one took it the next step and hocked up some phlegm and slagged that chunky mess on the window.  I would also like to add that this was while the teacher was in the room and they could see her.
Then on Friday she said a girl walked past the art-room and licked the same window.
Seriously?
She is a local, she must know what else has been on that window... mustn't she?